1. Field of the Invention
This invention relates to improved internal fixation means used in surgical procedures to treat fractured bones, pending fractures of bones, non-unions, arthritis, as well as any other procedure in which an attempt is made to surgically fuse two or more bones. More particularly, this invention relates to an orthopedic surgical implant and its method of use for stabilizing the relative position between a bone having a medullary canal and an adjoining bone or bone section.
2. Description of the Related Art
In recent years, both solid and tubular, metal rods or intramedullary nails have gradually gained importance in orthopedic surgery. They have in many situations become the standard surgical implant for stabilizing fractures or pending fractures in large tubular bones, such as the femur (thigh bone), tibia (leg bone) or humerus (upper arm bone).
The shape and configuration of such intramedullary nails has been a topic of much inventive effort. From initially circular or almost circular cross-sections, these nails have, in order to minimize the damage done to the bone during their placement in the body, come to be designed such that their cross-sections correspond to the anatomy of the medullary canals in which they are to be used.
For example, for the humerus bone, in which the medullary canal is not round along its entire length but is in fact flat and thin in the distal part, a nail with a flattened cross-section for its distal end has been developed. See U.S. Pat. No. 6,231,576.
In order to avoid the rotation of bone fragments and their shortening in multifragmented fractures, these nails have come to be used with various accessories, such as anchoring screws and other elongated, blade-like elements, that pass through holes in such nails and attach to the various bone fragments. See U.S. Pat. Nos. 5,928,235, 6,077,264, 6,235,031 and 5,562,667 for examples of such elements and their methods of use for stabilizing fractures of the neck of the femur.
Despite the extensive development of such intramedullary nails and accessories, they continue to exhibit certain disadvantages. For example, their designs are such that: (1) they often offer only minimal flexibility in addressing situations in which the bones or bone fragments to be stabilized have unique geometries or orientations, (2) they often involve relatively complex designs which tend to increase their costs of manufacture, and (3) their uses have heretofore been confined primarily to the treatment of fractures and pending fractures in individual large, tubular bones and for limited fusions of the ankle and knee - they have also been used in situations to stabilize one or several bones, but (4) they do not provide stability in all three, orthogonal planes of motion. Thus, there exists a continuing need for the development of new and improved intramedullary fixation devices.
Recognizing the need for the development of improved intramedullary fixation means, the present invention is generally directed to satisfying the needs set forth above and overcoming the disadvantages identified with prior art devices.
In accordance with one preferred embodiment of the present invention, the foregoing need can be satisfied by providing an intramedullary fixation device for use in fixing the relative position between a bone having a medullary canal and an adjoining bone or section of bone. Such a device comprises: (1) an intramedullary nail that is to be inserted into the medullary canal of the tubular bone whose position is to be fixed, with this nail having distal and proximate ends, a longitudinal axis extending between the ends, the proximate end terminating in a proximate end cross section that intersects the longitudinal axis of the nail, a threaded bore that extends from the proximate end cross section and along a specified portion of the longitudinal axis of the nail, and an opening situated along the length of the nail and extending through the nail and thorough which additional support screws or other attachment means can pass for further fixing the position of the nail, (2) an elongated blade for insertion into the adjoining bone whose position is to be fixed relative to that of the tubular bone, with this blade having distal and proximate ends, a longitudinal axis extending between these ends, top and bottom surfaces that extend between the ends, a passageway adjacent the proximate end that extends between the top and bottom surfaces, with the blade proximate end being configured so as to aid the passage of this end through the bone, and with the angle of intersection of the nail proximate end cross section with the nail""s longitudinal axis being chosen so as to set the desired angle of intersection between the longitudinal axes of the nail and blade, (3) a washer for use when the nail""s design is such that its proximate end section is not perpendicular to its longitudinal axis, with this washer having a top and a bottom surface, a longitudinal axis extending between these washer surfaces and an aperture extending between these surfaces, with the washer top surface being oriented so that it intersects the washer""s longitudinal axis at an angle which is complementary to the angle of intersection of the nail proximate end section with the nail""s longitudinal axis so as to allow the longitudinal axes of the washer and nail to coincide when the washer top surface fully contacts the nail""s proximate end section, and (4) a screw having a threaded section and a screw head, the threaded section configured so as to allow the screw to extend through the washer and blade passageway and into the nail""s threaded bore, with the screw head configured so that when the threaded section is fully screwed into the nail""s threaded bore the screw head presses against the washer""s bottom surface so as to lock the screw, washer, blade and nail together so as to prevent relative movement between these elements.
According to a second embodiment of the present invention, the intramedullary fixation device further comprises the blade distal end terminating in a distal end cross section that intersects the longitudinal axis of the blade. An orifice extends from this distal end cross section, between the blade""s top and bottom surfaces, and parallel to a specified portion of the longitudinal axis of the blade. This orifice is provided in order to allow for the initial insertion of a guide pin that is used to guide the precise placement of the blade in the adjoining bone.
According to a third embodiment of the present invention, a method is provided for stabilizing a specified, relative position between a tubular bone having a medullary canal and an adjoining bone or section of bone. This method comprises the steps of providing the listed elements for the fixation device and then seating the intramedullary nail and blade in the respective tubular and adjoining bones, and inserting the fixation means through a blade passageway and into a nail threaded bore so as to lock the elements together and prevent relative movement between the treated bones.
There has been summarized above, rather broadly, the more important features of the present invention in order that the detailed description that follows may be better understood and appreciated. In this regard, it is instructive to also consider the objectives of the present invention.
Thus, it is an object of the present invention to provide an intramedullary fixation device and method that offers maximum flexibility in addressing situations in which the bones or bone fragments to be stabilized have unique geometries or orientations.
It is another object of the present invention to provide an intramedullary fixation device that is simple to construct and use and whose manufacturing costs may be kept to a minimum.
It is yet another object of the present invention to provide an intramedullary fixation device and method that can be used for treating situations other than just the treatment of fractures and pending fractures in individual large, tubular bones. For example, to treat the situation in which the position of two or more adjoining bones are stabilized in order to allow and promote surgical fusion, or arthrodesis, of these bones. Some examples of such non-fracture, clinical applications include arthritis, infection, neuropathy and deformity.
It is a further object of the present invention to provide a method and device for providing stabilization of the relative position between two or more bones that may or may not share adjacent surfaces (e.g., the tibia, talus and calcaneus).
It is a still further object of the present invention to provide a device and method that will advance the utility of intramedullary nails in orthopedic medicine.
These and other objects and advantages of the present invention will become readily apparent as the invention is better understood by reference to the accompanying drawings and the detailed description that follows.
Thus, there has been summarized above, rather broadly, the more important features and objectives of the present invention in order that the detailed description that follows may be better understood and appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject matter of any eventual claims to this invention.